/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.db.utils.windowing.runtime;

import org.apache.iotdb.commons.concurrent.IoTDBThreadPoolFactory;
import org.apache.iotdb.commons.concurrent.IoTThreadFactory;
import org.apache.iotdb.commons.concurrent.ThreadName;
import org.apache.iotdb.db.conf.IoTDBDescriptor;
import org.apache.iotdb.db.rescon.AbstractPoolManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class WindowEvaluationTaskPoolManager extends AbstractPoolManager {

    private static final Logger LOGGER =
            LoggerFactory.getLogger(WindowEvaluationTaskPoolManager.class);

    private WindowEvaluationTaskPoolManager() {
        final int nThreads = IoTDBDescriptor.getInstance().getConfig().getWindowEvaluationThreadCount();
        LOGGER.info("WindowEvaluationTaskPoolManager is initializing, thread number: {}", nThreads);
        pool =
                new ThreadPoolExecutor(
                        nThreads,
                        nThreads,
                        0L,
                        TimeUnit.MILLISECONDS,
                        new LinkedBlockingQueue<>(
                                IoTDBDescriptor.getInstance().getConfig().getMaxPendingWindowEvaluationTasks()),
                        new IoTThreadFactory(ThreadName.WINDOW_EVALUATION_SERVICE.getName()));
    }

    public void submit(WindowEvaluationTask task) {
        try {
            super.submit(task);
        } catch (RejectedExecutionException e) {
            task.onRejection();
        }
    }

    @Override
    public Logger getLogger() {
        return LOGGER;
    }

    @Override
    public String getName() {
        return "window evaluation task";
    }

    @Override
    public void start() {
        if (pool != null) {
            return;
        }

        pool =
                IoTDBThreadPoolFactory.newFixedThreadPool(
                        IoTDBDescriptor.getInstance().getConfig().getWindowEvaluationThreadCount(),
                        ThreadName.WINDOW_EVALUATION_SERVICE.getName());
    }

    public static WindowEvaluationTaskPoolManager getInstance() {
        return WindowEvaluationTaskPoolManager.InstanceHolder.INSTANCE;
    }

    private static class InstanceHolder {

        private InstanceHolder() {
            // nothing to do
        }

        private static final WindowEvaluationTaskPoolManager INSTANCE =
                new WindowEvaluationTaskPoolManager();
    }
}
